Early fluid activity on Ryugu inferred by isotopic analyses of carbonates and magnetite

Kaitlyn A. McCain, Nozomi Matsuda, Ming-Chang Liu, Kevin D. McKeegan, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Naoya Imae, Masayuki Uesugi, Naoki Shirai, Takuji Ohigashi, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe & Yuichi Tsuda 

Nature Astronomy
Published: 12 January 2023


“Samples from asteroid Ryugu returned by the Hayabusa2 mission contain evidence of extensive alteration by aqueous fluids and appear related to the CI chondrites. To understand the sources of the fluid and the timing of chemical reactions occurring during the alteration processes, we investigated the oxygen, carbon and 53Mn–53Cr systematics of carbonate and magnetite in two Ryugu particles. We find that the fluid was initially between 0 and 20 °C and enriched in 13C, 17O and 18O, and subsequently evolved towards lighter carbon and oxygen isotopic compositions as alteration proceeded. Carbonate ages show that this fluid–rock interaction took place within approximately the first 1.8 million years of Solar System history, requiring early accretion either in a planetesimal less than ∼20 km in diameter or within a larger body that was disrupted and reassembled.”